30317

Appears in sequences

• Numbers k such that sopf(k) = (1/2)*(sopf(k+1) + sopf(k-1)), where sopf(x) = sum of the distinct prime factors of x.at n=10A075846
• Number of planar n X n X n binary triangular grids symmetric under 120 degree rotation with no more than 12 ones in any 5 X 5 X 5 subtriangle.at n=9A153997
• Auxiliary c(n) sequence used to prove some properties about Rowland's sequence. c(n) has the following recursive definition: c(1) = 5, c_(n+1) = c(n) + lfp(c(n)) - 1, where lpf(.) denotes the lowest prime factor of a number.at n=36A190894